train of thought

再び，JT OnlineにあったIchiro's achievement testament to his driveという記事から。
On that train of thought, it's worth noting that through 18 professional seasons Rose had played in 2,830 games and had 3,557 hits. Ichiro after Thursday's game — counting his time with Orix — had 10 games left in his 18th professional season and 3,508 hits in 2,559 games.
…Rose's train of thought on Ichiro is understandable. He's proud of his status as the Hit King and has to know Ichiro could surpass him in the minds of many when the whole of their careers are laid out side by side.
http://search.japantimes.co.jp/cgi-bin/sp20100925jc.html
今回注目したのはtrain of thoughtという表現です。何となく意味は掴めますが，辞書で調べてみると，trainには「（できごと・観念などの）連続，連鎖，一連（of）」という意味があり，My train of thought was interrupted by a phone call.（電話が鳴って私の思考の流れはとぎれた）という例文も挙げられていました（『スーパーアンカー英和辞典』第4版，学研教育出版）。
「一連の」というと(a) string of~や(a) stream of~がすぐに想起されますが，Googleで調べてみると，(a) string of thoughtや(a) stream of thoughtという用法はあるものの，train of thoughtの数には遠く及びません。よって，対象がthoughtの場合はtrainを使うのが適当のようです。（院生 小山本）